1. Field of the Invention
This invention relates to a technique of a writing instrument capable of transforming between a flat form and a tridimensional form.
2. Description of the Background Art
A writing instrument such as a ballpoint pen with a rod-like form is widely prevalent. Therefore, a writing instrument capable of transforming from a flat form like a card is desired in light of portability.
About such a writing instrument, there is a technology disclosed in, for example, Japanese Unexamined Patent Publication No. 2003-48395. This technology enables to certainly grip the writing instrument by folding down the rectangular card so that the ballpoint pen core fixed along the diagonal line is sandwiched and inserting a figure into the through-hole provided in the card at the time of the writing.
However, according to the above technology, the thickness becomes only approximately doubled even though the thin card is folded down, and it is difficult to get a good grip feeling which is equivalent to a writing instrument having a rod-like tridimensional form.